diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-01 16:44:06 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-01 16:44:06 -0700 |
commit | f359287765c04711ff54fbd11645271d8e5ff763 (patch) | |
tree | 73792cb8ca8ca289e66d18356667a781b3408eb7 /fs/open.c | |
parent | 8b39a57e965403c12a27d0859901a8a7d1d7318f (diff) | |
parent | c8ffd8bcdd28296a198f237cc595148a8d4adfbe (diff) |
Merge branch 'from-miklos' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
"Assorted patches from Miklos.
An interesting part here is /proc/mounts stuff..."
The "/proc/mounts stuff" is using a cursor for keeeping the location
data while traversing the mount listing.
Also probably worth noting is the addition of faccessat2(), which takes
an additional set of flags to specify how the lookup is done
(AT_EACCESS, AT_SYMLINK_NOFOLLOW, AT_EMPTY_PATH).
* 'from-miklos' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: add faccessat2 syscall
vfs: don't parse "silent" option
vfs: don't parse "posixacl" option
vfs: don't parse forbidden flags
statx: add mount_root
statx: add mount ID
statx: don't clear STATX_ATIME on SB_RDONLY
uapi: deprecate STATX_ALL
utimensat: AT_EMPTY_PATH support
vfs: split out access_override_creds()
proc/mounts: add cursor
aio: fix async fsync creds
vfs: allow unprivileged whiteout creation
Diffstat (limited to 'fs/open.c')
-rw-r--r-- | fs/open.c | 58 |
1 files changed, 45 insertions, 13 deletions
diff --git a/fs/open.c b/fs/open.c index 719b320ede52..e62b1db06638 100644 --- a/fs/open.c +++ b/fs/open.c @@ -345,21 +345,14 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len) * We do this by temporarily clearing all FS-related capabilities and * switching the fsuid/fsgid around to the real ones. */ -long do_faccessat(int dfd, const char __user *filename, int mode) +static const struct cred *access_override_creds(void) { const struct cred *old_cred; struct cred *override_cred; - struct path path; - struct inode *inode; - int res; - unsigned int lookup_flags = LOOKUP_FOLLOW; - - if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ - return -EINVAL; override_cred = prepare_creds(); if (!override_cred) - return -ENOMEM; + return NULL; override_cred->fsuid = override_cred->uid; override_cred->fsgid = override_cred->gid; @@ -394,6 +387,38 @@ long do_faccessat(int dfd, const char __user *filename, int mode) override_cred->non_rcu = 1; old_cred = override_creds(override_cred); + + /* override_cred() gets its own ref */ + put_cred(override_cred); + + return old_cred; +} + +long do_faccessat(int dfd, const char __user *filename, int mode, int flags) +{ + struct path path; + struct inode *inode; + int res; + unsigned int lookup_flags = LOOKUP_FOLLOW; + const struct cred *old_cred = NULL; + + if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ + return -EINVAL; + + if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) + return -EINVAL; + + if (flags & AT_SYMLINK_NOFOLLOW) + lookup_flags &= ~LOOKUP_FOLLOW; + if (flags & AT_EMPTY_PATH) + lookup_flags |= LOOKUP_EMPTY; + + if (!(flags & AT_EACCESS)) { + old_cred = access_override_creds(); + if (!old_cred) + return -ENOMEM; + } + retry: res = user_path_at(dfd, filename, lookup_flags, &path); if (res) @@ -435,19 +460,26 @@ out_path_release: goto retry; } out: - revert_creds(old_cred); - put_cred(override_cred); + if (old_cred) + revert_creds(old_cred); + return res; } SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) { - return do_faccessat(dfd, filename, mode); + return do_faccessat(dfd, filename, mode, 0); +} + +SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode, + int, flags) +{ + return do_faccessat(dfd, filename, mode, flags); } SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) { - return do_faccessat(AT_FDCWD, filename, mode); + return do_faccessat(AT_FDCWD, filename, mode, 0); } int ksys_chdir(const char __user *filename) |